1. Field of the invention
The present invention relates to a projection type image display device, and more specifically relates to a projection type image display device for projecting images on a screen from its rear surface to display the images on the screen.
2. Description of the Background Art
Conventionally known projection type image display devices include a rear projection type image display device for projecting images from a projection unit onto a screen from its rear surface. In a commonly used rear projection type image display device, a screen unit with a screen is attached by screws and the like from the rear surface of a casing storing therein a projection unit and others to the front surface of the casing, in a manner that allows the screen unit to be detached from the casing. As a result of a trend toward reduced space for placing a projection type image display device in recent years, a newly developed projection type image display device is such that the rear surface of a casing can closely contact a wall, and all maintenance work can be performed from the front surface of the casing. So, the simple and cost-saving structure of such a projection type image display device is required.
A projection type image display device for which maintenance can be performed from the front surface of a casing is introduced for example in Japanese Patent Application Laid-Open No. 2005-221834. According to the projection type image display device introduced therein, fall and the like of a screen unit during attachment or detachment thereof is prevented, so the screen unit can be attached and detached with a high degree of reliability.
According to the disclosure of Japanese Patent Application Laid-Open No. 2005-221834, parts should be changed as a result of the change in size of a screen or a casing. Further, a large number of parts constituting the projection type image display device results in a complicated structure thereof. So, assembly of the device requires much time and high cost. Still further, it is hard to make fine adjustment in attaching the screen unit to the casing. So, when the screen unit slides forward from the casing, the screen unit goes out of its adjustment position. As a result, when a plurality of projection type image display devices are arranged (vertically and horizontally), neighboring screen units may be damaged by contacting with each other.